It's not allowed.
Some professionals have analyzed that no matter which measurement principle is used, with the existing technology, smart bracelets are not yet able to accurately measure blood pressure.
And the smart bracelet is a new thing, because it does not belong to the medical equipment, the country has not yet had the relevant testing standards. Dr. Wang Guofu said that the results of the smart bracelet measurement is for reference only, and can never replace the sphygmomanometer as the basis for diagnosis and treatment. Because for hypertensive patients, different blood pressure values, doctors will have different medication programs.
Extended information
Legally marketed and illegally sold
Blood pressure monitors registered through China's State Food and Drug Administration (CFDA) can only be legally marketed and sold within China? [1]?
On the contrary, any blood pressure measurement product that is not registered by the China State Food and Drug Administration (CFDA) is not legal to be marketed and sold within China, regardless of the manufacturer's claim that its product is a medical device.
Accuracy of blood pressure watches
Strictly speaking, blood pressure monitors that are registered by China's State Food and Drug Administration (CFDA) are accurate.
Baidu Encyclopedia - Watch Blood Pressure Monitor